She had survived two assassination attempts, one in 2009 and another in 2010. The first claimed the life of her husband.

But in the middle of the month, Maria Santos Gorrostieta Salazar’s luck ran out. The former mayor of the Mexican town of Tiquicheo was found dead in a field on 17 November. Her body bore evidence of torture; she had also been stabbed several times. The autopsy showed she had died from severe trauma to the cranium. She was 36, and the mother of three young children.

Gorrostieta Salazar’s punishment didn’t fit her crime: as mayor of Tiquicheo, a pueblo in the central state of Michoacán – a hotbed of drug trafficking – she had sought justice and fought against corruption. She refused to resign in spite of the assassination attempts by suspected members of drug cartels.

With more than 50,000 deaths related to the drug war since President Felipe Calderón took office in 2006 (and launched a military-led, heavy-handed crackdown on the nation’s cartels) it is easy to look at those such as Gorrostieta Salazar as heroes, or martyrs. And though they may warrant such posthumous praise, it’s wiser to look at these heroes as ordinary people, in order to understand the situation in Mexico today.

Drug cartels have not taken over Mexico, they have grown within it. In countless towns and even some of the bigger cities, there are only a handful of routes for the average young man or woman to take in life: policeman, soldier, journalist, public official, if one is ambitious enough and has the right connections and savvy, mayor.

These people grow up together; they know each other; some take the high road and others the low.

Countless police officials have been accused of corruption in recent years; some, including the nation’s drug tsar, have been found guilty. In August this year, four senior Mexican army officers were charged with alleged links to drug traffickers, too, rankling the good military men involved in the fight.

Being earnest

Earnest politicians face hard struggles. Aaron Irizár López, a former mayor of Culiacán, a violence-plagued city in Sinaloa, explained this to me back in 2009.

As mayor, Irizár had pledged to crack down on certain illicit activities – prostitution, for instance – and received death threats as a result. But he persevered in spite of the risks. He grew up in a small town about 50 miles from Culiacán; some of his peers from his schooldays became drug traffickers.

“Some are in jail, some are dead,” he said, smiling somewhat sadly. “Others are rich.”

It is this web of crime, corruption and collusion that is holding Mexico back and making it so difficult for trust between law-enforcement agencies to develop, and for public confidence in politicians and the system to grow.

Erica Garza (not her real name) worked for years with her husband on the federal investigative police force, known as the AFI. They had met in training – he was her instructor – and she was attracted to his honesty, his optimism. “He had a different way of looking at the world, and at the way things should be,” she recalls. “He wanted things to be the way they should be – not the way they were.”

Her husband sought to implement changes in a corrupt federal force, but met resistance from subordinates who had ties to organised crime. He fought those challenges, and rose through the ranks. The “Incorruptible”, as Erica calls her husband, faced enemies at every turn.

Several years ago, he was paid a visit by a group of traffickers. They wanted to negotiate a deal to leave them alone. He refused.

Thirteen days later, he was driving home from his office in Mexico City when another vehicle sped up from behind. They blocked him into a corner. The assailants got out of the car and opened fire.

No investigation followed his death; this continues to trouble Erica. She’s still in law enforcement, and goes to work every day even though she believes some of her co-workers were responsible for organising the hit on her husband. She continues her work not to be a heroine but because she wants to change things in Mexico for the sake of her children. But it’s not easy; every day, she has to look at colleagues whom she perceives as the enemy.

“Among them is the person who killed my husband,” she says. Also at the back of her mind is one, somewhat reluctant, request for a chance to do things over again. “I’m proud that my husband was an honest person,” she says. “But sometimes I think, ‘Why weren’t you corrupt?’”

If he had been, he might be alive today. If she had been tempted to cross the thin line to the other side, Maria Santos Gorrostieta Salazar might be, too.

Malcolm Beith is the author of “The Last Narco: Hunting El Chapo, the World’s Most Wanted Drug Lord” (Penguin, £9.99)